Effect of dietary L-carnitine on growth performance and body composition in nursery and growing-finishing pigs.

Two experiments were conducted to determine the effect of dietary L-carnitine on growth performance and carcass composition of nursery and growing-finishing pigs. In Exp. 1,216 weanling pigs (initially 4.9 kg and 19 to 23 d of age) were used in a 35-d growth trial. Pigs were blocked by weight in a randomized complete block design (six pigs per pen and six pens per treatment). Four barrows and four gilts were used to determine initial carcass composition. L-Carnitine replaced ground corn in the control diets to provide 250, 500, 750, 1,000, or 1,250 ppm. On d 35, three barrows and three gilts per treatment (one pig/block) were killed to provide carcass compositions. L-Carnitine had no effect (P > 0.10) on growth, percentages of carcass CP and lipid, or daily protein accretion. However, daily lipid accretion tended to decrease and then return to values similar to those for control pigs (quadratic P < 0.10) with increasing dietary L-carnitine. In Exp. 2, 96 crossbred pigs (initially 34.0 kg BW) were used to investigate the effect of increasing dietary L-carnitine in growing-finishing pigs. Pigs (48 barrows and 48 gilts) were blocked by weight and sex in a randomized complete block design (two pigs/pen and eight pens/treatment). Dietary L-carnitine replaced cornstarch in the control diet to provide 25, 50, 75, 100, and 125 ppm in grower (34 to 56.7 kg; 1.0% lysine) and finisher (56.7 to 103 kg; 0.80% lysine) diets. At 103 kg, one pig/pen was slaughtered, and standard carcass measurements were obtained. Dietary L-carnitine did not influence growth performance (P > 0.10). However, increasing dietary carnitine decreased average and tenth-rib back-fat (quadratic, P < 0.10 and 0.05), and increased percentage lean and daily CP accretion rate (quadratic, P < 0.05). Break point analysis projected the optimal dosage to be between 49 and 64 ppm of L-carnitine for these carcass traits. It is concluded that dietary carnitine fed during the nursery or growing-finishing phase had no effect on growth performance; however, feeding 49 to 64 ppm of L-carnitine during the growing-finishing phase increased CP accretion and decreased tenth-rib backfat.     

Evaluation of conjugated linoleic acid and dietary antibiotics as growth promotants in weanling pigs.

An experiment was conducted to determine the efficacy of dietary conjugated linoleic acid (CLA) as a growth promotant in weanling swine. Weanling pigs (n = 192; 7.6 kg and 29 d of age) were randomly assigned to four treatments that were arranged as a 2 x 2 factorial. Concentrations of dietary CLA (0 or 0.6%) and antibiotics (+/-) constituted the main effect variables. Dietary CLA treatments consisted of a 1% addition of an oil containing 60% CLA isomers or 1% soybean oil, and dietary antibiotic treatments were antibiotics or no antibiotics. The experimental diets were fed for 9 wk in four phases (1, wk 1; 2, wk 2 and 3; 3, wk 4 through 6; and 4, wk 7 through 9), after which all pigs were fed identical medicated diets for the duration of the finishing phase. Live weights were recorded at wk 17 postweaning and at marketing to determine any residual effects of dietary treatments on finisher ADG and days to market. Medicated diets fed during phases 1 and 2 contained 55 mg carbadox/kg; during phase 3 contained 299 mg tilmicosin/kg; and during phase 4 contained 110 mg tylosin and 110 mg sulfamethazine/kg. Pigs fed medicated diets had higher overall ADG than pigs fed unmedicated diets for wk 0 through 9 (P < 0.03). Gain:feed (G:F) was greater for pigs fed medicated diets than for pigs fed unmedicated diets during phase 1 (P < 0.03) and for the duration of the nursery phase (P < 0.03). There were no effects of CLA on ADG, ADFI, or G:F. There were no residual effects of nursery CLA or antibiotics on finisher ADG and days to market. Blood samples collected from a subset of pigs (n = 72) at the completion of phases 2, 3, and 4 were assayed for serum IGF-I and antibody concentrations to porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae. There was a tendency for pigs fed medicated diets to have greater IGF-I concentrations than pigs fed unmedicated diets at the completion of phase 4 (P < 0.06). Pigs fed CLA had greater antibody titers (P < 0.02) to Mycoplasma hyopneumoniae at d 63 than pigs fed diets without CLA. These results indicate that feeding 0.6% dietary CLA did not enhance growth performance in weanling swine and that the use of dietary antibiotics can increase production efficiency in nursery pigs. Furthermore, there were no interactions between CLA and dietary antibiotics on the variables addressed in this study.     

共轭亚油酸对断奶仔猪生产性能及免疫的影响

试验选择30日龄、体重相近的杜×长×大三元杂交断奶仔猪40头,按体重和性别随机分为4个组,公母各半。各组在相同基础日粮中分别添加0%、0.5%、1.0%和2.0%共轭亚油酸(CLA),研究日粮中添加CLA对断奶仔猪生产性能与免疫的影响。结果表明,当日粮中CLA的添加量为1.0%和2.0%时,可以显著提高断奶仔猪试验末重、日增重、饲料利用率、IgM水平、T淋巴细胞转化率、CD4 及CD4 /CD8 比例,降低仔猪采食量及腹泻率(P<0.05)。而对IgG、IgA水平及CD8 无显著影响(P>0.05)。     

Effects of conjugated linoleic acid on the belly firmness and fatty acid composition of genetically lean pigs.

A study of the effects of conjugated linoleic acid (CLA) on the belly firmness and fatty acid composition of genetically lean pigs was conducted. From 75 to 120 kg live weight, 30 gilts were allowed ad libitum access to a corn-soybean meal diet supplemented with either 1% CLA oil (CLA-60) or 1% sunflower oil (SFO) or were fed the sunflower oil-supplemented diet restricted to the amount consumed by pigs fed the CLA-60 diet (RSFO). Conjugated linoleic acid oil consists of 60% positional and geometric isomers of CLA. Pigs fed SFO exhibited higher average daily gains (0.98 vs 0.80 kg/d, P < 0.01) than RSFO-fed pigs, but there were no effects of dietary treatment on feed intake or feed efficiency. Dietary treatment did not affect (P > 0.05) backfat thickness or longissimus muscle area. Bellies of gilts fed CLA-60 were subjectively evaluated to be firmer (2.91 vs 2.43 or 2.07 +/- 0.13, P < 0.01) than those of SFO- or RSFO-fed gilts, respectively. The longissimus muscle of gilts fed CLA-60 contained more saturated fatty acids (39.77 vs. 36.04 or 36.73 +/- 0.74%, P < 0.001) and less unsaturated fatty acids (60.23 vs 63.96 or 63.27 +/- 0.74%, P < 0.001) than that of gilts fed SFO or RSFO, respectively. The belly fat of gilts fed CLA-60 contained more saturated fatty acids (44.45 vs. 37.50 or 36.60 +/- 0.46%, P < 0.001) and less unsaturated fatty acids (54.78 vs. 61.75 or 62.47 +/- 0.46%, P < 0.001), resulting in lower iodine values (57.69 vs 66.37 or 65.62 +/- 0.91, P < 0.001) than that of gilts fed SFO or RSFO, respectively. Gilts fed CLA-60 accumulated more CLA in the longissimus muscle (0.55 vs 0.09 or 0.09 +/- 0.03%, P < 0.01) and belly fat (1.56 vs. 0.13 or 0.13 +/- 0.15%, P < 0.001) than did gilts fed SFO or RSFO, respectively. Dietary treatment did not affect (P > 0.05) 24-h pH, drip loss or subjective quality evaluations of the longissimus muscle. The effect of supplemental CLA to improve belly firmness is of practical significance and may provide a nutritional solution to carcass fat and belly firmness problems, thereby enhancing the overall value of extremely lean carcasses.     

Effects of dietary zinc and iron supplementation on mineral excretion, body composition, and mineral status of nursery pigs

Two experiments were conducted to evaluate the effects of dietary Zn and Fe supplementation on mineral excretion, body composition, and mineral status of nursery pigs. In Exp. 1 (n = 24; 6.5 kg; 16 to 20 d of age) and 2 (n = 24; 7.2 kg; 19 to 21 d of age), littermate crossbred barrows were weaned and allotted randomly by BW, within litter, to dietary treatments and housed individually in stainless steel pens. In Exp. 1, Phases 1 (d 0 to 7) and 2 (d 7 to 14) diets (as-fed basis) were: 1) NC (negative control, no added Zn source); 2) ZnO (NC + 2,000 mg/kg as Zn oxide); and 3) ZnM (NC + 2,000 mg/kg as Zn Met). In Exp. 2, diets for each phase (Phase 1 = d 0 to 7; Phase 2 = d 7 to 21; Phase 3 = d 21 to 35) were the basal diet supplemented with 0, 25, 50, 100, and 150 mg/kg Fe (as-fed basis) as ferrous sulfate. Orts, feces, and urine were collected daily in Exp. 1; whereas pigs had a 4-d adjustment period followed by a 3-d total collection period (Period 1 = d 5 to 7; Period 2 = d 12 to 14; Period 3 = d 26 to 28) during each phase in Exp. 2. Blood samples were obtained from pigs on d 0, 7, and 14 in Exp. 1 and d 0, 7, 21, and 35 in Exp. 2 to determine hemoglobin (Hb), hematocrit (Hct), and plasma Cu, (PCu), Fe (PFe), and Zn (PZn). Pigs in Exp. 1 were killed at d 14 (mean BW = 8.7 kg) to determine whole-body, liver, and kidney mineral concentrations. There were no differences in growth performance in Exp. 1 or 2. In Exp. 1, pigs fed ZnO or ZnM diets had greater (P < 0.001) dietary Zn intake during the 14-d study and greater fecal Zn excretion during Phase 2 compared with pigs fed the NC diet. Pigs fed 2,000 mg/kg, regardless of Zn source, had greater (P < 0.010) PZn on d 7 and 14 than pigs fed the NC diet. Whole-body Zn, liver Fe and Zn, and kidney Cu concentrations were greater (P < 0.010), whereas kidney Fe and Zn concentrations were less (P < 0.010) in pigs fed pharmacological Zn diets than pigs fed the NC diet. In Exp. 2, dietary Fe supplementation tended to increase (linear, P = 0.075) dietary DMI, resulting in a linear increase (P < 0.050) in dietary Fe, Cu, Mg, Mn, P, and Zn intake. Subsequently, a linear increase (P < 0.010) in fecal Fe and Zn excretion was observed. Increasing dietary Fe resulted in a linear increase in Hb, Hct, and PFe on d 21 (P < 0.050) and 35 (P < 0.010). Results suggest that dietary Zn or Fe additions increase mineral status of nursery pigs. Once tissue mineral stores are loaded, dietary minerals in excess of the body's requirement are excreted.     

Effects of dietary conjugated linoleic acid on fatty acid composition, lipid oxidation, color, and water-holding capacity of pork loin

The effects of dietary conjugated linoleic acid (CLA) on fatty acid composition, lipid oxidation, and pork quality were investigated. Pigs (n = 20) were fed a diet containing 0, 1, 2.5, or 5% CLA for 4 wk and slaughtered at 105 kg. The longissimus thoracis et lumborum muscle was collected at 24 h postmortem. Pork loin chops (3 cm thick) were packaged aerobically and stored at 4 degrees C for 7 d. Samples were analyzed for ultimate pH, intramuscular fat content, fatty acid composition, thiobarbituric acid-reactive substances, color (L*, a*, b*), and water-holding capacity. Dietary CLA reduced the concentration of linoleic acid and increased CLA concentration in intramuscular fat of pork loin (P < 0.05). The concentration of CLA in muscle was increased with dietary CLA level and did not change during storage. Thiobarbituric acid-reactive substance value of control was higher than that of the CLA-fed groups (P < 0.05). Intramuscular fat content was increased by dietary CLA, and less purge loss was observed with samples from CLA-fed pigs (P < 0.05). Dietary CLA improved the color stability of pork loin during cold storage. After 7 d, lightness (L*) and yellowness (b*) of the 5% CLA-fed group were significantly lower than those of control (P < 0.05). The results indicated that the water-holding capacity of pork loin was increased with increased intramuscular fat content apparently caused by dietary CLA. Also, the data indicated that color stability of pork was improved with inhibition of lipid oxidation and changing of fatty acid composition by dietary CLA.     

Effects of dietary supplementation with conjugated linoleic acid on fatty acid composition and lipid oxidation in chicken breast meat

We investigated the effects of dietary conjugated linoleic acid (CLA) on fatty acid composition and lipid oxidation in breast meat of broiler chickens. Broiler chickens (28-day-old females) were fed diets containing experimental oils at 20 g/kg diet for 28 days. The experimental oils consisted of either a 2:0, 1:1, or a 0:2 (wt : wt) ratio of safflower oil (high linoleic acid content) to a commercial CLA mixture. In this study, dietary CLA supplementation significantly increased the composition and content of CLA in chicken meat. The predominant CLA in meat from birds with supplemented diets was the cis -9, trans -11 isomer. The proportion of saturated fatty acid in meat significantly increased with increasing CLA supplementation, with a corresponding decrease in monounsaturated fatty acid. Dietary CLA also reduced thiobarbituric acid reactive substances (TBARS) values in raw meat during storage at 4°C for 5 days. These results provide evidence that CLA feeding is a practical strategy not only for adding nutritional benefits to chicken meat but also for improving meat quality including oxidative stability.     

Synergistic effects of betaine and conjugated linoleic acid on the growth and carcass composition of growing Iberian pigs

An experiment was conducted to determine the efficacy of dietary betaine, CLA, or both as growth promotants and carcass modifiers in growing Iberian pigs. Twenty gilts (20 kg of BW) were individually penned and fed barley- and soybean meal-based diets (12% CP, 0.81% Lys, and 14.8 MJ of ME/kg of DM) containing either no added betaine or CLA (control), 0.5% betaine, 1% CLA, or 0.5% betaine + 1% CLA, at 95% of ad libitum energy intake. An additional group of 5 pigs was slaughtered at the beginning of the experiment to obtain the initial body composition. At 30 kg of BW, a balance experiment was conducted. At 50 kg of BW, pigs were slaughtered and viscera was removed and weighed. Betaine or CLA alone did not affect growth performance. However, betaine + CLA increased ADG (601 vs. 558 g, P = 0.03) and gain relative to ME intake (25.4 vs. 22.2 g/MJ, P = 0.03) compared with control pigs. Digestibility of nutrients and metabolizability of energy did not differ among diets (P = 0.46 to 0.75). Carcass protein, water, and lean deposition (g/d) increased (19.8, 24.2, and 23.4%, respectively, P < 0.01) in pigs fed betaine + CLA compared with control pigs. Similarly, protein deposition relative to ME intake increased by 28% in betaine + CLA-supplemented pigs (P < 0.05). Fat and mineral deposition did not differ among treatments. Carcass protein, water, and lean content (g/kg of carcass) of pigs fed betaine + CLA-supplemented diets tended to increase (P = 0.07 to 0.09) and carcass fat content tended to decrease (P = 0.09). Similarly, estimated composition of carcass gain was affected, such that water and lean content tended to increase (P = 0.06 to 0.08), whereas fat tended to decrease (P = 0.08) in pigs fed betaine + CLA-supplemented diets. Longissimus muscle area was not altered by treatments (P = 0.49). The liver of pigs fed betaine + CLA diets had increased weight (19%, P < 0.05) compared with control pigs. Overall, dietary supplementation of betaine + CLA increased ADG, protein, water, and lean deposition in growing Iberian gilts. There appears to be a synergistic action when betaine and CLA are used together.     

Effect of trans-10 cis-12 conjugated linoleic acid on bovine oocyte competence and fatty acid composition

The reproductive performance of dairy cows may be improved by feeding conjugated linoleic acid (CLA) supplements during early lactation. The mechanism of action of t10,c12 CLA is not clearly known. Our objective was to investigate the effect of t10,c12 CLA on oocyte maturation and lipid composition of cumulus oocyte complexes (COC). The developmental potential of oocytes incubated in in vitro maturation (IVM) medium supplemented with t10,c12 CLA to the blastocyst stage and embryo quality were also assessed. In experiment 1, abattoir-derived oocytes were matured in TCM199 + 10% serum supplemented with 100 μM t10,c12 CLA (t10,c12 CLA n = 672) or without it (control n = 672). Mature oocytes were either stained for chromatin configuration or inseminated and cultured for embryo development assessment. In experiment 2, COC and IVM culture media were subjected to fatty acid (FA) analysis prior and after maturation with t10,c12 CLA or without it (control). Total lipids and FA profiles in oocytes, cumulus cells and culture media were determined by gas chromatography. t10,c12 CLA supplementation to IVM medium improved (p = 0.05) embryo quality evaluated morphologically. This effect was associated with t10,c12 CLA presence (3.1 ± 0.7%, p = 0.04) and lower levels of arachidonic acid in FA profile of t10,c12 CLA mature oocytes (immature oocytes = 4.4 ± 1.9%, t10,c12 CLA mature oocytes = 1.0 ± 0.7%, p = 0.05). Differences in myristic and eicotrienoic acids, saturated and unsaturated FA concentrations between oocytes and cumulus cells were detected (p ≤ 0.05). In conclusion, the presence of t10,c12 CLA during maturation interfered on lipid metabolism improving bovine oocyte competence to develop into higher quality embryos.     

添加共轭亚油酸对肉鸡胴体品质和肌肉成分影响的研究

试验选用迪高肉鸡100羽(公母各半),随机分为4个处理(P>0.05);饲料中分别添加共轭亚油酸(CLA)为0%、0.25%、0.5%、1%。进行为期60d的饲养试验。试验结束后屠宰,研究CLA不同添加水平对肉鸡胴体品质和肌肉成分的影响。结果表明:与对照组相比,各处理组屠宰率都有所提高;添加0.25%、1%共轭亚油酸与对照组相比全净膛率分别提高0.99(P>0.05)、2.86个百分点(P<0.01),添加0.5%共轭亚油酸与对照组相比下降0.66个百分点(P<0.05);添加0.25%、1%共轭亚油酸与对照组相比半净膛率分别提高0.29(P>0.05)、3.74个百分点(P<0.01),添加0.5%共轭亚油酸与对照组相比下降0.74个百分点(P>0.05);试验组与对照组相比腹脂率分别提高0.18、0.37、0.61个百分点,但差异不显著;肌肉失水率方面差异不显著;肌肉嫩度分别下降7.12(P<0.01)、0.06(P>0.05)、1.26N(P>0.05);肌肉熟肉率分别提高0.34(P>0.05)、0.78(P>0.05)、4.98个百分点(P<0.01);肌肉粗蛋白含量随着饲料中CLA添加量的提高有不同程度的提高,但差异不显著(P>0.05);肌肉粗脂肪含量添加量为0.50%、1.0%时有不同程度的升高,但差异不显著(P>0.05);添加量为0.25%、1%时肌肉粗灰分的含量随之降低,与对照组相比差异极显著(P<0.01),添加量为0.5%时肌肉粗灰分含量有所上升,但差异不显著(P>0.05)。     

共轭亚油酸的生理作用及其在养殖业的应用前景

共轭亚油酸（CLA）是在双键位置和几何构型上呈异构形式亚油酸的异构体复合物，有１０多种存在形式。CLA是食物中的天然成分，普遍存在于反刍动物性食品如牛奶、奶酪、牛肉、羊肉及脂肪中，脂肪中的CLA含量最高，一般为２．９～８．９２mg／g。自然状态下瘤胃中细菌的亚油酸异构化作用能够产生CLA，因此反刍动物肉及乳品中CLA含量比其它动物高，猪肉及禽肉中的CLA含量相对较少。２０世纪７０年代末，MichaelPariza在烹调过程中寻找肉中诱导有机体突变物质的形成时偶尔发现CLA的存在。Pariza（１９８５）的研究表明，CLA能降低小…     

Effect of conjugated linoleic acid on energy metabolism in growing-finishing pigs

The effect of conjugated linoleic acid (CLA) on energy metabolism was studied in a respiration experiment with 20 growing pigs. From 70 kg liveweight onwards the animals received isoenergetic rations containing 0 or 3% CLA on the basis of metabolic bodyweight. Between 95 and 100 kg liveweight the gas exchange of each animal was measured over 48 h in a respiration chamber. This was preceded by a 5‐day quantitative determination of faeces and urine. The heat production and energy retention of the animals were determined by the carbon–nitrogen balance technique and the RQ method. Additionally several parameters of blood serum were determined. CLA had no effect on digestibility and metabolizability of energy, nor were gas exchange and heat production (HP) of the animals affected by the treatment. Average heat production across all measurements was 628 kJ/kg W^0.75 in the control group and 636 kJ/kg W^0.75 in the CLA group. No difference in fat deposition was observed (control 386, CLA group 379 kJ/kgW^0.75). The N balance on the other hand was 2.2 g/day higher in the CLA‐supplemented animals. This caused retained protein energy, as a proportion of total energy retention, to increase from 24.2 to 25.8%. The ratio of retained protein energy to fat energy was 10% higher in the CLA‐treated animals than in the controls. Body mass increase over the trial as a whole was unaffected (control 27.6, CLA group 28.1 kg, equivalent to daily gains of 931 and 946 g, respectively). Blood serum lipoproteins exhibited few CLA‐induced changes. The greatest effects were observed in triacylglycerols, which were raised in the CLA animals compared with the controls. The ratio of cholesterol‐low‐density lipoprotein to cholesterol‐high‐density lipoprotein rose by 17% as a result of CLA treatment. Serum concentrations of albumin, creatinine, urea and glucose were unchanged. In conclusion, the study showed that supplementation with CLA under isoenergetic feeding conditions with a strongly positive energy balance has no marked effect on total metabolism, although a slightly enhanced deposition of protein was evident.     

Effect of dietary conjugated linoleic acid and monounsaturated fatty acids on productive, carcass and meat quality traits of pigs

Three levels (0, 1 and 2%) of conjugated linoleic acid (CLA) were combined with two levels (low and high) of monounsaturated fatty acids (MUFA) for pig feeding. Productive, carcass and meat quality traits were studied. Large White ♂ × Landrace × Large White ♀ gilts (n = 288) weighting 70 kg were randomly allotted to 6 different feeding treatments and fed to a final average weight of 107 kg. Loins were taken from 48 animals (8 animals randomly selected from each treatment). No differences due to dietary CLA, MUFA or CLA × MUFA interaction were found on average daily gain, average daily consumption, feed conversion ratio, carcass yield, backfat thickness, loin weight, loin pH and loin colour. A significant increase in intramuscular fat content (p = 0.010) and in saturated fatty acids (SFA) (p < 0.001), and a decrease in MUFA (p = 0.001) and desaturase indices were found as consequence of dietary CLA, regardless the MUFA level. Therefore, dietary CLA, MUFA and their interaction did not influence productive and carcass traits of pigs. However, the use of CLA for swine feeding increased the intramuscular fat content and modified the fatty acid profile, regardless the MUFA level of the diets.     

共轭亚油酸对蛋鸡生产性能及蛋黄腊肪酸含量的影响

本文旨在研究不同共轭亚油酸(CLA)添加水平对蛋鸡生产性能及蛋黄脂肪酸含量的影响.选用30周龄罗曼商品蛋鸡96只,随机分成4个处理组,每个处理组6个重复,每个重复4只鸡,分别饲喂添加0%、0.5%、1%和2%共轭亚油酸的基础日粮,试验期为印d.结果表明,添加共轭亚油酸对蛋鸡生产性能、蛋黄重量和蛋黄脂肪含量的影响不显著,但添加1.0%和2.0%共轭亚油酸,鸡的采食量和蛋清重显著降低(P<0.05);随着日粮共轭亚油酸添加水平的提高,蛋黄中胆固醇和单不饱和脂肪酸含量降低(P<0.05),蛋黄中饱和脂肪酸、多不饱和脂肪酸和共轭亚油酸含量显著提高(P<0.05).本试验条件下,2%共轭亚油酸添加组对于提高蛋黄的共轭亚油酸含量,降低蛋黄的胆固醇含量效果最佳.     

瘤胃保护共轭亚油酸和亚油酸对奶牛产奶性能的影响

选择健康、泌乳月份与产奶量相近的多胎荷斯坦泌乳牛20头,随机分成5组,每组4头,研究日粮中添加商业来源的瘤胃保护共轭亚油酸钙盐(Ca-CLA)同时添加自然来源亚油酸(葵花油)对奶牛生产性能的影响。试验期为52d。对照组基础日粮为60%粗饲料(苜蓿、羊草、青贮)和40%精料(以DM为基础),处理组在对照组日粮基础上分别添加Ca-CLA100g/d·头(CLA)、葵花油350g/d·头(Sunf);Ca-CLA100g/d·头 葵花油350g/d·头(CLA Sunf),Ca-CLA50g/d·头 葵花油175g/d·头(1/2CLA 1/2Sunf)。结果表明:在奶牛日粮中,单独添加自然来源亚油酸产奶量较对照组差异不显著(P>0.05),而单独添加共轭亚油酸钙盐或与自然来源亚油酸高低不同剂量添加产奶量较对照组都分别显著提高2.20%、9.95%、11.16%,无论单独添加自然来源亚油酸或Ca-CLA或二者以高低不同剂量同时添加,牛奶的乳脂率较对照组都分别显著降低15.0%,6.24%,21.74%,14.35%。总之,奶牛日粮中同时添加Ca-CLA和自然来源亚油酸能显著提高产奶量,降低乳脂率,并且,减少Ca-CLA的添加量同时添加自然来源亚油酸可以达到高剂量添加Ca-CLA相同的效果。     

日粮共轭亚油酸对黄羽肉鸡生长性能、腹脂沉积的影响

共轭亚油酸（CLA）是必需脂肪酸亚油酸的立体和位置异构体的混合物，是一种新型功能性脂肪酸，具有多种生理功能。而近年来的研究表明，动物口粮中添加共轭亚油酸安全无毒性，可以明显降低脂肪沉积，改善肉品质。但这类研究多以啮齿动物为研究对象，而以家禽为研究对象方面的资料较为缺乏。在养禽业中，肉鸡腹脂沉积过多会影响胴体的商品价值。因此，为了更好地了解共轭业油酸对肉鸡生产的影响，本试验以黄羽肉鸡为受试动物，通过在日粮中添加共轭亚油酸，研究其生长性能、腹脂沉积及肉质的变化等。     

日粮共轭亚油酸对黄羽肉鸡生长性能及血清中瘦素和脂联素的影响

选用60只1日龄黄羽肉鸡,研究共轭亚油酸(CLA)对其生长性能、腹脂沉积的影响。结果显示,日粮中添加CLA可显著提高49日龄黄羽肉鸡腿肌重(P<0.05),显著降低母鸡的腹脂沉积(P<0.05),但对母鸡的体增重有抑制作用(P<0.05),且能提高血清中瘦素水平(P<0.05)。     

Influence of a conjugated linoleic acid mixture on growth, organ weights, carcass traits and meat quality in growing pigs

Grain soybean meal diets, either with 2% of a conjugated linoleic acid (CLA) preparation or with 2% rapeseed oil (control), were tested in 2 × 40 pigs, Pietrain × (Landrace × Large White), each group with 20 female in the live weight range 23.5–117.0 kg and 20 male-castrated pigs in the live weight range 23.5–110.6 kg. The CLA-content of the preparation amounted to 54.0% cis / trans + trans / cis , 8.7% cis/cis and 32.7% trans / trans isomers. Daily weight gain, feed intake and feed : gain ratio were not influenced by the diets tested. The carcass lean increased significantly from 57.2% of the control group to 58.7% in the CLA group (p   < 0.05). The male-castrated showed a stronger CLA effect than the female pigs – not only was the carcass lean significantly increased by 2%, but backfat thickness was significantly decreased by 2.8 mm, i.e. minus 11% (as compared with barrows of the control). The meat of CLA-fed pigs had a higher conductivity. A CLA effect on further meat quality characteristics (pH 45 min post-mortem, impedance, colour criteria, intramuscular fat, drip loss, frying loss, shear force, sensory attributes) could not be detected. There were some significant correlations between the meat quality attributes.     

酵母培养物对保育猪的生长性能、肠道健康和免疫应答的影响

216头断奶仔猪用于测定日粮中添加不同含量的酵母培养物(YC)对断奶仔猪的生长性能、养分消化率、肠道形态结构、肠道菌群和免疫应答的影响,并测定YC是否能够替代抗生素生长抑制剂(AGP)。试验1,28日龄断奶仔猪192头(体重为7.5±0.2kg)随机分配到6个处理组:①对照组(没有添加AGP或YC);②AGP组(氯四环素,80mg/kg);③2.5g/kgYC组(益康XP酵母培养物);④5g/kgYC组;⑤10g/kgYC组;⑥20g/kgYC组。每个处理组8个重复栏,每栏4头断奶仔猪,试验期21d。5g/kgYC组的平均日增重(ADG)高于对照组和其他YC组(p<0.05),而所有YC组AGP组之间没有差异。5g/kgYC组、10g/kgYC组和AGP组的平均日采食量(ADFI)高于对照组(p<0.01);而增重/耗料比(G:F)没有受到影响。因此,试验2选用了添加5g/kgYC的日粮。试验2,24头保育猪(21日龄,体重为5.8±0.1kg)随机分成3个处理组试验21d以阐述YC的作用机理。处理组为:①对照组(没有添加AGP或YC);②AGP组;③5g/kgYC组。每周采集血样测定CD4+、CD8+的百分...